Threaded leveling feet are known and used widely for supporting and leveling furniture and appliances. FIG. 7 of the present application, for example, illustrates a known prior art leveling foot used commonly in metal cabinetry, desks, and other furniture applications. The prior art leveling foot of FIG. 7 comprises generally a head member 3 coupled to a threaded shaft 5 adjustably disposed through a weld nut or other threaded member 7, which is welded or otherwise fastened directly on an underside 9 of the furnishing supported thereby.
The prior art leveling foot of FIG. 7 however is relatively rigid, and has a tendency to damage furniture during handling and moving thereof. More particularly, compressive loads applied axially along the threaded shaft 5 impart forces to the furniture that tend to cause buckling thereof, for example along the sides and corners of metal desks and file cabinets. Also, shear forces applied transversely to the threaded shaft 5 tend to bend the shaft or the underside 9 of the furniture, sometimes separating the weld nut 7 from the furniture, and often deforming outer side portions thereof.
The furniture industry has adopted general standards or guidelines against which leveling foot performance is evaluated. These guidelines include the American National Standard ANSI/BIFMA drop test and leg strength, or shear, test and apply generally to furniture, including metal desks and file cabinets, that is moved frequently. The relatively rigid prior art leveling foot of FIG. 7, and other similar supports, however, are relatively susceptible to damage that may render the furniture unserviceable as defined by industry standards.
The prior art leveling foot of FIG. 7 is also relatively costly to manufacture and install. The head member 3 may be formed, for example in a stamping operation, and then fastened to the threaded shaft 5, for example by welding or by staking. The bore, or hole, in the furniture underside 9 that accommodates the weld nut 7 is fabricated generally by a drilling or stamping operation, and where the underside 9 is recessed to accommodate the weld nut 7 as in FIG. 7, additional tooling or forming operations are required. Thereafter the weld nut 7 is welded or otherwise fastened to the underside 9 of the furniture.
The prior art leveling foot of FIG. 7 is most often formed of metal, which has a tendency to oxidize and become unsightly. Over time, oxidation may interfere with or prevent adjustment of the leveling foot, and may ultimately degrade the structural integrity thereof. To address these problems, the metal may be treated or coated, but this further increases costs, which is undesirable.
It is also known generally in the appliance industry to fabricate leveling feet from plastic materials, as illustrated in prior art FIG. 8 of the present application. The appliance industry has however adopted different test standards for leveling feet than the furniture industry, since appliances like washing and drying machines and kitchen ranges tend to be relatively stationary after installation and are not moved about as frequently as is furniture. FIG. 8 illustrates a known prior art appliance industry plastic leveling foot having a relatively thick threaded shaft 11 with an acme or an American national screw thread adjustably disposed through a threaded opening in an underside 13 of the appliance.
The known plastic leveling feet of the appliance industry are relatively rigid, and have a tendency to break and cause damage to the appliance when subject to compressive and shear forces, as discussed above regarding the prior art leveling foot of FIG. 7. Known prior art plastic appliance leveling feet may also have a relatively square corner 12 between the bottom surface of the foot member and the sides thereof. The foot and particularly the square corner thereof tends to be obstructed easily by floorings having discontinuous surfaces, typical of some tile floorings, which may cause the threaded shaft 11 to break or cause damage to the underside 13 of the appliance when subject to excessive shear forces.
FIG. 8 also illustrates a prior art threaded screw opening characterized generally by an upper lip portion 14 and a lower lip portion 15 formed for example in a stamping operation. The known prior art stamped threaded openings typical of the appliance industry generally reduce costs associated with fastening a nut thereto by welding, but the stamped threads tend to concentrate the load unduly on portions of the threaded shaft, which has a tendency to fail. Prior art stamped threaded openings tend also not to distribute the load evenly about the threaded shaft, producing greater loads on one side of the shaft than on the other side thereof. FIGS. 8 and 9 illustrate an edge 16 of the lower lip portion 15 imparting most all of the forces to the threaded shaft 11 along a line portion on a surface 18 thereof extending only partially thereabout. This concentrated load renders the threaded shaft 11 highly susceptible to failure, particularly on the side thereof where the load is applied. Not surprisingly, prior art plastic leveling feet and the stamped threaded openings of the appliance industry perform unacceptably when subject to compressive and shear loads characteristic of the furniture industry.
The present invention is drawn toward advancements in the art of leveling feet, and more particularly to threaded leveling feet for supporting and leveling furniture, including metal desks and file cabinets, and systems therefor.
It is an object of the invention to provide novel leveling feet and systems therefor that are economical and that overcome problems in the prior art.
It is another object of the invention to provide novel leveling feet and systems therefor that are relatively strong and reliable, and more particularly leveling feet and systems therefor that better comply with furniture industry standards.
It is also an object of the invention to provide novel leveling feet that better absorb impact shock thereto thereby reducing shock loads imparted to the article supported thereby, and to provide leveling foot systems that better distribute loads relatively uniformly and over relatively large surface areas.
It is a more particular object of the invention to provide novel leveling feet, useable for supporting and leveling furniture and other articles, comprising generally a threaded shaft having a lead end portion and a resilient head disposed on a foot end portion thereof, the head having a curved flange portion curving generally radially outwardly from the threaded shaft with increasing axial distance from the foot end portion thereof, whereby the head is relatively flexible to absorb impact shock directed toward the threaded shaft.
It is a more particular object of the invention to provide novel leveling feet systems, useable for supporting and leveling furniture and other articles, comprising generally a leveling foot having a threaded shaft with a lead end portion, and a foot end portion with a head. The threaded shaft has screw threads disposed helically thereabout, and the screw threads have a leading side configured at an angle. An opening disposed through a plate member has a partially circumferential helical edge extending helically from a first side thereof. The helical edge is defined by a helical surface portion of the plate member having an outer surface at an angle substantially equal to the angle of the leading side of the screw thread, and disposed at least partially about the opening. The lead end portion of the threaded shaft is disposable into and partially through the opening of the furniture plate member from the second side thereof by rotatably engaging the screw threads with the helical edge, and the helical surface portion of the furniture plate member is engageable with a surface area of the leading side of the screw thread to support the article.